The present invention relates to IP (Internet Protocol) telephony services.
The present invention therefore has applications in the field of voice on IP, but also in other fields, such as Internet videoconferencing.
IP telephony, sometimes called Internet telephony, and often abbreviated as “VoIP” (Voice over IP), is a technique which makes it possible to communicate via the Internet network, or any other network accepting the TCP/IP protocol. Unlike STN (switched telephone network) or RTC (from the French “Réseau téléphonique Commuté”) depending on dedicated telephone exchanges, IP telephony allows the transport of telephone conversations over the whole of the digital or analog network accepting the TCP/IP protocol, for example Ethernet, ISDN (Integrated Services Digital Network) or RNIS (from the French “Réseau Numérique à Intégration de Services”), PPP (Point-to Point Protocol), etc.
A user of a given IP telephony service has client equipment, for example domestic equipment, configured for this IP telephony service. The client equipment typically comprises a terminal to provide a user interface. The client equipment also comprises a home gateway to provide the interface with the IP network in accordance with the given IP telephony service.
“Home Gateway” is understood to mean a client gateway, that is to say a gateway located at the user end, unlike a network equipment situated in the network under the control of an operator. It may for example be a gateway for domestic use within a home, or it may be a gateway for professional use within a business. In general, it is a gateway for client use.
The user of an IP telephony service may converse with any other user of the same IP telephony service, that is to say with any other user having a client equipment configured for that IP telephony service.
FIG. 1 shows an example of communication between users of a same IP telephony service.
Two users, Bob and Alice, of this IP telephony service have equipments 7 and 9 respectively, each comprising a terminal 1, 5, connected to a home gateway 2, 4. The gateways 2, 4 provide an interface between the terminals 1, 5 and the internet 3.
The terminals 1, 5 may be of various types, for example a conventional fixed telephone, a mobile telephone, personal digital assistant, a computer provided with an IP telephony service, etc.
There are however various IP telephony services, possibly offered by different operators.
A user of a first IP telephony service, referred to as the caller, may wish to converse with a user of a second IP telephony service, distinct from the first service, referred to as the recipient.
The caller may then, for example, configure his client equipment so that he may himself become a user of the second IP telephony service.
According to another possibility, the communication between the two users Bob and Alice may be carried out via a centralized gateway 8 installed between the networks of the two IP telephony service providers, as shown in FIG. 2.
In this example, the data exchanged between Bob and Alice pass through the centralized interconnection gateway 8, which makes it possible to convert the data transmitted by Bob in accordance with one of the two IP telephony services into data in accordance with the other IP telephony service, and vice-versa.
The centralized interconnection gateway 8 is managed by the operators of the two IP telephony services, and may cover a relatively wide geographic area, comprising for example a whole country.
According to a third possibility and insofar as the recipient has an E164 number (commonly called a “telephone number”), data may be exchanged by means of two transits, as shown in FIG. 3.
The data exchanged pass through two centralized interconnection gateways 10, 11.
The data sent by the caller Bob flows in the IP network as far as the gateway 10. It is then converted into data in accordance with a format adapted to STN before arriving at the gateway 11. The data then undergoes a second conversion in order to flow on the IP network as far as the recipient Alice. In the other direction, the data sent by Alice is first converted by the gateway 11 and then by the gateway 10.
The gateways 10, 11 are managed in a centralized manner, and may cover a relatively wide geographic area, comprising for example several countries.
Furthermore, the possibility of communication shown in FIG. 3 may only be envisaged insofar as Alice has an E164 number.